Adjustable-camber aerofoil



H. D. ROCHEVILLE ADJUSTABLE CAMBER AEROFOIL Feb. 3, 1931.

Filed Mar ch 25, 1929 I 2 Sheets-Sheet 1 A TTORNEYJ Feb. 3, 1931. H. D. ROCHEVILLE ADJUSTABLE CAMBER AEROFOIL Filed March 25. 1929 2 Sheets-Sheet 2 m fl N 9% R Q h. MN 3 W. W

BY M ATTORNEYS.

Patented Feb. 3, 1931 UNITED STATES HARRY I). BOOHEVILLE, OF LOS ANGELES, CALIFORNIA ADJUSTABLE-CALIBER AEROFOIL Application filed March 25, 1929. Serial No. 349,619.

This invention relates to aeroplane aerofoils, such as the supporting planes and appertains particularly to a variable curvature of the cross section longitudinally of the aerofoil. As illustrative of the inventive idea, an aerofoil curve known as the Clark Y or modification thereof are commonly. used for speed, while a more arched curve known as the Gottingen 387 or modifications there- 1 of have greater sustaining power with relation to head resistance than the Clark Y or modifications. An aerofoil having a Gottingen 387 curve or modification is more useful to secure great lift at slow speeds so as to add to the stability of an aeroplane in taking off and in landing. It is desirable to have a Gottingen 387 curve or modifications thereof for taking off and landing and a Clark Y curve or modifications thereof for cruising or making speed. The present invention relates to an aerofoil structure arranged so that the thickness of the aerofoil and its curvature may be changed.

I The objects of this invention are to provide an aerofoil having any or all of the following features: a variable camber; an aero foil structure operable at the W111. of the pilot to change the thickness of the aerofoil; an aerofoil structure of the character before described in which the curvature maybe changed from one predetermined limitlng curve to another; an aerofoil structure as before described wherein the curvature may set at any intermediate curve between the limiting curves; an aerofoil of the character described having a pivoted trailing edge portion and mechanism to effect such changes in the aerofoil.

These objects together with other ob ects in corresponding accomplishment are obtained by means of the embodiment of my invention, illustrated in the accompanying drawing, in which Fig. 1 is a plan view of a fragment of a fuselage showing. one aerofoil with the covering broken away to show the frame work; Fig. 2 is a section from front to rear of an aerofoil in collapsed position; Fig, 1s a similar cross section with the aerofoil in expanded condition; and Fig. 4 is a fragmental section at right angles to Figs. 2 and 3.

Referring more particularly to the drawings, A indicates the fuselage of an aeroplane, only a fragment thereof being shown. Mounted on the fuselage in any suitable manner is shown an aerofoil embodyin my invention. This aerofoil is shown wit an entering or front portion 13 and a trailing portion or flap C. The trailing portion C is pivotally connected to the entering portion and may be maintained in adjusted position by means hereafter described. The arrangement is such as to change the camber of the aerofoil with change in pivotal position of the trailing portion. An aileron D of any well known type of construction is provided on the trailing port-ion and completes the aerofoil.

Referring to the front portion of the aerofoll, a spar 6 extends the length thereof adacent the entering edge and a spar 7 is provided at the rear of the front port-ion. The spars 6 and 7 are preferably built up includmg braces so that lattice spars are provided for passage therethrough of the operating parts of the aerofoil frame. The front portion has a frame work consisting of alternate fixed and variable ribs. The fixed ribs are marked 8 and may be of the usual construction. These ribs are anchored to a nose piece 10 extending across the entering edge. As illustrative of the invention, the fixed rib is shown with :1 Clark Y curve.

The Variable rib comprises an upper covermg supporting section including articulated rafters, each rafter consisting of joints marked 11a, 11b and 110. Joints 11a are hmged as indicated by 12 to the cross member 10. Joints 117) are hinged to joints 11a as indicated by 13, and joints 110 are con nected by elongated slot and pin connections 14. The joints 110 are connected by hinges to the spar 7 A ointed stretcher spans each rafter. Each stretcher comprises a joint 16a connected to a joint 16?) by an elongated slot and pin connection 17. Joints 16a are pivotally connected by the hinge 12 to the cross I nember 10. Joints 166 are connected to the oints llcby hinges 18. Arms 19 are provided on the stretcher joints 16?). A yoke 20 is provided on each rafter joint 16?; for the accommodation of eccentrics. The rafters arestiffened by suitable braces and connected to the stretcher joints by brace members 21. A shaft 22 extends the length of the variable ribs and has mounted thereon eccentrics 23 operating in the yokes 20, so that upon rotation of the shaft, the variable rafters will be raised or lowered to change the upper curve. The shaft 22 extends toward the fuselage and any suitable mechanism may be rovided for turnin the shaft from the fuseage. Such mechanism forms no part of the present invention and is not shown herein. The ribs are provided with a suitable flexible covering 24 which follows the variable ribs in their changes. In the arms 19 are holes.

The trailing portion 0 of the aerofoil consists of a rigid frame 25 built up in any suitable manner and having a covering 26. Tuxtending across the front of the trailing portion is a cross member 27 hinged at 28 to the spar 7 so that the trailing portion may be rocked through an angle. Gusset members 29 are provided in the angular opening between the cross member 27 and the spar 7. Tying the cross member 27 to the arm 19 are tie members 30; It will be noted that upon buckling of the stretcher, the trailing portion will be swung downwardly.

In the drawing, the variable ribs when in their upper osition are shown to'form substantially a gottingen 387 curve. Movement of the eccentric shaft 22 causes the upper covering to be arched to a greater curvature and the aerofoil to be thickened. At the same time the trailing portion is rocked downwardly so that the trailing portion acts as an air brake and will decrease the speed. The amount of angle of the trailing portion may be adjusted by the tie member through a turn buckle 31 or by changing the tie member connection'between the arm 18 and the gusset members 29 using different holes. Thus, adjustability of the angle of the trailing portion is provided for. In taking off, the aerofoil may be thickened, and after a suitable altitude has been reached, the aerofoil may be collapsed. Tn landing the aerofoil may be again thickened. This is done at the will of the pilot. It will be noted that the fixed ribs maintain constant the shape of the lower side of the aerofoil and limit the shape of the upper side at its minimum thickness. In design, the positions of the yokes 20 and eccentrics in relation to the stretchers affects the curvature as well as the location of connections 13 in the articulated rafters.

What I claim is 1. An aerofoil comprising a front section and a trailing section; said front section having a covering, a frame supporting said covering and including a set of spaced ribs having jointed rafters and a set of fixed rafters,

jointed stretchers supporting the set of articulated rafters, a shaft extending transverse of said ribs, means securing said stretchers to said shaft whereby turning of said shaft bends said stretchers; the trailing section of said aerofoil being pivotally mounted on said front section; an adjustable tie member securing said trailing section to said stretchers to cause rocking of said trailing section with movement of said rafters whereby to change the camber of said aerofoil.

2. An aerofoil structure having a frame for determining the curvature of the upper side and the thickness of the aerofoil: said frame comprising a set of fixed ribs maintaining constant the shape of the lower side of the aerofoil; a set of articulated ribs determining an adjustable curvature of the upper side of said aerofoil, said articulated ribs being pivoted at their front and rear ends in relation to said fixed ribs, each of said articulated ribs comprising .a rafter having joints with a plurality of pivotal connections intermediate the ends thereof, and a stretcher having a pivotal connection intermediate its ends whereby it may be buckled; and adjustable means to buckle the stretchers and maintain them in adjusted buckled positions.

3. An aerofoil structure having a frame for determining the curvature of the upper side and the thickness of the aerofoil: said frame comprising a set of fixed ribs maintaining constant the shape of the lower side of the aerofoil; a set of articulated ribs determining an adjustable curvature of the upper side of said aerofoil, said articulated ribs being pivoted at their front and rear ends in relation to said fixed ribs, each of said articulated ribs comprising a rafter having three joints intermediate its ends secured together by pivotal connections and a stretcher having a single pivotal connection intermediate its ends and located intermediate said pivotal connections in its rafter; and adjustable means to buckle the. stretchers and maintain them in adjusted buckled PL itions.

4:. An aerofoil structure having a frame for determining the curvature of the upper side and the thickness of the aerofoil: said frame comprising a set of fixed ribs maining said yokes whereby to adjustably buckle said stretchers and maintain them in adjusted buckled positions.

5. An aerofoil structure having a frame for determining the curvature of the upper side and the thickness of the aerofoil: said frame comprising a set of fixed ribs maintaining constant the shape of the lower side of the aerofoil; a set of articulated ribs determining an adjustable curvature of the upper side of said aerofoil, said articulated ribs being pivoted at their front and rear ends in relation to said fixed ribs, each of said articulated ribs comprising a rafter having three joints intermediate its ends secured together by pivotal connections and a stretcher having a single pivotal connection intermediate its ends and located intermediate said pivotal connections in its rafter; eccentric yokes on said stretchers, and eccentrics journalled on said fixed ribs and engaging said yokes where- L y to adjustably buckle said stretchers and maintain them in adjusted buckled positions. 6. An aerofoil structure having a frame for determining the curvature of the upper side and the thickness of the aerofoil: said frame comprising a set of fixed ribs maintaining constant the shape of the lower side of the aerofoil; a set of articulated ribs determining an adjustable curvature of the upper side of said aerofoil, said articulated ribs being pivoted at their front and rear ends in relation to said fixed ribs each of said articulated ribs comprising a rafter having joints with a plurality of pivotal connections intermediate the ends thereof, and a stretcher having a pivotal connection intermediate its ends whereby it may be buckled; eccentric yokes on corresponding joints of said stretchers, and eccentrics journalled on said fixed ribs and engaging said yokes whereby to adjustably buckle said stretchers and maintain them in adjusted buckled positions.

7 An aerofoil structure having a frame for determining the curvature of the upper side and the thickness of the aerofoil: said frame comprising a set of fixed ribs maintaining constant the shape of the lower side of the aerofoil; a-set-of articulated ribs determining an adjustable curvature of the up per side of said aerofoil, said articulated ribs being pivoted at-their front and rear ends in relation to said fixed ribs, each of said articulated ribs comprising a rafter having three joints intermediate its ends secured together by pivotal connections and a stretcher having a single pivotal connection intermediate its ends and located intermediate said pivotal connections in its rafter; eccentric yokes on correspondingjoints of said stretchers, and eccentrics journalled on said fixed ribs and engaging said yokes whereby to adjustably buckle said stretchers and maintain them in adjusted buckled positions.

8. An aerofoil structure having a frame for determining the curvature of the upper side and the thickness of theaerofoil: said frame comprising a set'of fixed ribs maintaining constant the shape of the lower side of the aerofoil and having rafters limiting the curvature of the upper side at the minimum thickness of said aerofoil; a set of articulated ribs determining an adjustable curvature of the upper side of said aerofoil, said articulated ribs being pivoted at their front and rear ends in relation to said fixed ribs, each of said articulated ribs comprising a rafter having joints with a plurality of pivotal connections intermediate the ends thereof, and a stretcher having a pivotal connection intermediate its ends whereby it may be buckled; and adjustable means to buckle the stretchers and maintain them in adjusted buckled position.

9. An aerofoil structure having a frame for determining the curvature of the upper side and the thickness of the aerofoil: said frame comprising a set of fixed ribs maintaining constant the shape of the lower side of the aerofoil and having rafters limiting the curvature of the upper side at the minimum thickness of said aerofoil; a set of articulated ribs determining an adjustable curvature of the upper side of said aerofoil, said articulated ribs being pivoted at their front and rear ends in relation to said fixed ribs, each of said articulated ribs comprising a rafter having three joints intermediate its ends secured together by pivotal connections and a stretcher having a single pivotal connection intermediate its ends and located intermediate said pivotal connections in its rafter; and adjustable means to buckle the stretchers and maintain them in adjusted buckled positions.

10. An aerofoil structure having a frame for determining the curvature of the upper side and the thickness of the aerofoil: said frame comprising a set of fixed ribs maintaining constant the shape of the lower side of the aerofoil and having rafters limiting the curvature of the upper side at the minimum thickness of said aerofoil; a set of articulated ribs determining an adjustable curvature of the upper side of said aerofoil, said articulated ribs being pivoted at their front and rear ends in relation to said fixed ribs,

each of said articulated ribs comprising a rafter having joints with a plurality of pivotal connections intermediate the ends thereof, and a stretcher having a pivotal connection intermediate its ends whereby it may be buckled; eccentric yokes on said stretchers, and eccentrics journalled on said fixed ribs and engaging said yokes whereby to adjustably buckle said stretchers and maintain them in adjusted buckled positions.

11. An aerofoil structure having a frame for determining the curvature of the upper side and the thickness of the aerofoil: said frame comprising a set of fixed ribs maintaining constant the shape of the lower side maintain them in adjusted buckled positions. of the aerofoil and having rafters limiting In witness that I claim the foregoing I have the curvature of the upper side at the minimum thickness of said aerofoil; a set of articulated ribs determining an adjustable curature of the upper side of said aerofoil, said articulated ribs being pivoted at their front and rear ends in relation to said fixed ribs each of said articulated ribs comprising a rafter having three joints intermediate its ends secured together by pivotal connections and a stretcher having a single pivotal connection intermediate its ends and located intermediate said pivotal connections in its rafter; eccentric yokes on said stretchers, and eccentrics journalled on said fixed ribs and engaging said yokes whereby to adjustably buckle said stretchers and maintain them in adjusted buckled positions.

12. A11 aerofoil structure having a frame ior determining the curvature of the upper side and the thickness of the aerofoil: said frame comprising a set of fixed ribs maintaining constant the shape of the lower side of the aerofoil and having rafters limiting the curvature of the upper side at the minimum thickness of said aerofoil; a set of articulated ribs determining an adjustable curvature of the upper side of said aerofoil, said articulated ribs being pivoted at their front and rear ends in relation to said fixed ribs, each of said articulated ribs comprising a rafter having joints with a plurality of pivotal connections intermediate the ends thereof, and a stretcher having a pivotal connection intermediate its ends whereby it may be buckled; eccentric yokes on corresponding joints of said stretchers, and eccentrics j ournalled on said fixed ribs and engaging said yokes whereby to adjustably buckle said stretchers and maintain them in adjusted buckled positions.

13. An aerofoil structure having aframc for determining the curvature of the upper side andthe thickness of the aerofoil: said frame comprising a set of fixed ribs maintaining constant the shape of the lower side of the aerofoil and having rafters limiting the curvature of the upper side at the minimum thickness of said aerofoil; a set of articulated ribs determining an adjustable curvature of hereunto subscribed my name this 12th day of March, 1929.

the upper side of said aerofoil, said articu- 

